Psoriasis is a chronic, non-infectious disease that affects mainly the skin. It is currently suspected to be autoimmune in origin. It commonly causes red, scaly patches to appear on the skin, although some patients have no dermatological symptoms. The scaly patches caused by psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly accumulates at these sites and takes on a silvery-white appearance. The disorder is a chronic recurring condition that varies in severity from minor localized patches to complete body coverage. The cause of psoriasis is not exact, but it is believed to have a genetic component and it can be triggered by a prolonged injury to the skin known as ‘Koebner phenomenon’.
Psoriasis is seen worldwide, in all races, and both sexes. Although psoriasis can be seen in people of any age, from babies to seniors, most commonly patients are first diagnosed in their early adult years.
Patients with more severe psoriasis may have social embarrassment, job stress, emotional distress, and other personal issues because of the appearance of their skin.
There are many treatments available, but because of its chronic recurrent nature, psoriasis is a challenge to treat. Amongst various treatments, topical treatment is widely used for the management of psoriasis. Ointment and creams containing coal tar, dithranol (anthralin), corticosteroids like desoximetasone (Topicort), fluocinonide, vitamin D3 analogues (for example, calcipotriol), and retinoids are routinely used.
Clobetasol propionate is a corticosteroid used to treat various skin disorders including eczema and psoriasis. Clobetasol belongs to US Class I (Europe: class IV), i.e. super potent of the corticosteroids, making it one of the most potent therapeutic regimen available for psoriasis. It comes in ointment, cream, gel, emulsion, aerosol foam, shampoo presentations. However, use of clobetasol is limited substantially due to its side effects such as burning sensation, itching, dryness and irritation.
U.S. Patent Publication No. 20060239929 discloses a method for treating psoriasis, by spraying onto the skin with psoriasis daily for at least 4 weeks a pharmaceutical composition containing an effective amount of clobetasol propionate. A preferred pharmaceutical composition contains clobetasol propionate, ethyl alcohol, isopropyl myristate, and anionic surfactant.
U.S. Patent Publication No. 20090047359 discloses an ointment for treating and curing skin diseases of human beings such as psoriasis, dermatitis, acne, herpes and fungi, consisting of a composition obtained based on ingredients such as white petrolatum, clobetasol propionate, distilled water, rosemary honey, virgin olive oil, white precipitate mercury chloride, salicylic acid, and gentian violet.
U.S. Pat. No. 5,629,021 relates to micellar nanoparticles and methods of their production.
U.S. Pat. No. 5,894,019 discloses topical compositions comprising lipid and essentially free of emulsifiers and surfactants.
European Patent No. EP 506197 B1 discloses an aqueous suspension of solid lipid nanoparticles for topical use.
European Patent No. EP 671903 B1 discloses topical compositions in the form of submicron oil spheres.
Most of the topical preparations contain vehicles comprising permeation enhancers, solvents, and high amount of surfactants to achieve these goals. But use of these agents is harmful, especially in chronic application, as many of them are irritants.
Therefore, there exists a need to develop such topical preparations of anti-psoriatic agents which does not involve use of such agents as described above to facilitate drug permeation through the skin, and still leads to excellent photostability, greater permeability, and improved bioavailability resulting in enhanced therapeutic activity.
The compositions of the invention overcome all the commonly encountered problems as exemplified above.